Methods of preparing a catalyst with low HRVOC emissions

ABSTRACT

A method of preparing a catalyst comprising a) drying a chrominated-silica support followed by contacting with a titanium(IV) alkoxide to form a metalized support, b) drying a metalized support followed by contacting with an aqueous alkaline solution comprising from about 3 wt. % to about 20 wt. % of a nitrogen-containing compound to form a hydrolyzed metalized support, and c) drying the hydrolyzed metalized support followed by calcination at a temperature in a range of from about 400° C. to about 1000° C. and maintaining the temperature in the range of from about 400° C. to about 1000° C. for a time period of from about 1 minute to about 24 hours to form the catalyst.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 15/953,927 filed Apr. 16, 2018, published as U.S.Patent Application Publication No. 2019/0314787 A1, and entitled“Methods Of Preparing A Catalyst With Low HRVOC Emissions,” which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to catalyst compositions. Morespecifically, the present disclosure relates to methods of preparingolefin polymerization catalyst compositions and polymers prepared fromsame.

BACKGROUND

An economically important class of olefin polymerization catalystsincludes chromium-silica-titanium catalysts. Enhancements in preparationmethods for olefin polymerization catalysts can reduce the costsassociated with catalyst production and improve process economics. Forexample, highly reactive volatile organic compounds (HRVOC) may beemitted during catalyst production. HRVOCs play a role in the formationof ozone in ozone nonattainment areas, i.e., areas that do not meet theEnvironmental Protection Agency's air quality standards for ground-levelozone. Consequently, processes that create HRVOC emissions may besubject to compliance with various state and federal regulationsregarding HRVOC emission, such as the HRVOC emissions cap and tradeprogram. Thus, there is an ongoing need to develop processes for theproduction of olefin polymerization catalysts that create minimal HRVOCemissions.

SUMMARY

Disclosed herein is a method of preparing a hydrolyzed pre-catalystcomprising a) drying a silica support by heating to a temperature in arange of from about 150° C. to about 250° C. and maintaining thetemperature in the range of from about 150° C. to about 250° C. for atime period of from about 1 hour to about 24 hours to form a driedsupport; b) contacting the dried support and a titanium(IV) alkoxide toform a titanated support; c) drying the titanated support by heating toa temperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature in the range of from about 50° C. to about200° C. for a time period of from about 30 minutes to about 6 hours toform a dried titanated support; d) contacting the dried titanatedsupport and an aqueous alkaline solution comprising from about 3 wt. %to about 20 wt. % of a nitrogen-containing compound for a time period offrom about 10 minutes to about 6 hours to form a mixture comprising ahydrolyzed titanated support wherein a weight ratio of the amount ofaqueous alkaline solution to the amount of titanium(IV) alkoxide in thedried titanated support is from about 30:1 to about 3:1; and e) removingthe hydrolyzed titanated support from the mixture comprising thehydrolyzed titanated support and drying the hydrolyzed titanated supportby heating to a temperature in a range of from about 50° C. to about200° C. and maintaining the temperature in the range of from about 50°C. to about 200° C. for a time period of from about 30 minutes to about6 hours to form the hydrolyzed pre-catalyst. The method may furthercomprise contacting a chromium-containing compound and the hydrolyzedpre-catalyst to form a pre-catalyst and calcining the pre-catalyst byheating to a temperature in a range of from about 400° C. to about 1000°C. and maintaining the temperature in the range of from about 400° C. toabout 1000° C. for a time period of from about 1 minute to about 24hours to form a catalyst.

Also disclosed herein is a method of preparing a hydrolyzed pre-catalystcomprising a) drying a silica support by heating to a temperature in arange of from about 150° C. to about 250° C. and maintaining thetemperature in the range of from about 150° C. to about 250° C. for atime period of from about 1 hour to about 24 hours to form a driedsupport; b) contacting the dried support and a titanium(IV) alkoxide toform a titanated support; c) heating the titanated support to atemperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature in the range of from about 50° C. to about200° C. while contacting the titanated support and an alkaline materialfor a time period of from about 2 hours to about 48 hours; d) ceasingcontacting of the titanated support and the alkaline material to providea hydrolyzed support having a temperature in a range of from about 50°C. to about 200° C.; and e) maintaining the temperature in the range offrom about 50° C. to about 200° C. for a time period of from about 30minutes to about 6 hours to form the hydrolyzed pre-catalyst. The methodmay further comprise contacting a chromium-containing compound and thehydrolyzed pre-catalyst and to form a pre-catalyst and calcining thepre-catalyst by heating to a temperature in a range of from about 400°C. to about 1000° C. and maintaining the temperature in the range offrom about 400° C. to about 1000° C. for a time period of from about 1minute to about 24 hours to form a catalyst.

Also disclosed herein is a method of preparing a catalyst comprising a)drying a chrominated-silica support by heating to a temperature in arange of from about 150° C. to about 250° C. and maintaining thetemperature in the range of from about 150° C. to about 250° C. for atime period of from about 1 hour to about 24 hours to form a driedchrominated-silica support; b) contacting the dried chrominated-silicasupport and a titanium(IV) alkoxide to form a metalized support; c)drying the metalized support by heating to a temperature in a range offrom about 50° C. to about 200° C. and maintaining the temperature inthe range of from about 50° C. to about 200° C. for a time period offrom about 30 minutes to about 6 hours to form a dried metalizedsupport; d) contacting the dried metalized support and an aqueousalkaline solution comprising from about 3 wt. % to about 20 wt. % of anitrogen-containing compound for a time period of from about 10 minutesto about 6 hours to form a mixture comprising a hydrolyzed metalizedsupport wherein a weight ratio of the amount of aqueous alkalinesolution to the amount of titanium(IV) alkoxide in the dried metalizedsupport is from about 30:1 to about 3:1; e) removing the hydrolyzedmetalized support from the mixture comprising the hydrolyzed metalizedsupport and drying the hydrolyzed metalized support by heating to atemperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature in the range of from about 50° C. to about200° C. for a time period of from about 30 minutes to about 6 hours toform a pre-catalyst; and f) calcining the pre-catalyst by heating to atemperature in a range of from about 400° C. to about 1000° C. andmaintaining the temperature in the range of from about 400° C. to about1000° C. for a time period of from about 1 minute to about 24 hours toform the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising a)drying a silica support by heating to a temperature in a range of fromabout 150° C. to about 250° C. and maintaining the temperature in therange of from about 150° C. to about 250° C. for a time period of fromabout 1 hour to about 24 hours to form a dried support; b) contactingthe dried support and a titanium(IV) alkoxide to form a titanatedsupport; c) drying the titanated support by heating to a temperature ina range of from about 50° C. to about 200° C. and maintaining thetemperature in the range of from about 50° C. to about 200° C. for atime period of from about 30 minutes to about 6 hours to form a driedtitanated support; d) contacting the dried titanated support and anaqueous alkaline solution comprising from about 3 wt. % to about 20 wt.% of a nitrogen-containing compound for a time period of from about 10minutes to about 6 hours to form a mixture comprising a hydrolyzedtitanated support wherein a weight ratio of the amount of aqueousalkaline solution to the amount of titanium(IV) alkoxide in the driedtitanated support is from about 30:1 to about 3:1; e) removing thehydrolyzed titanated support from the mixture comprising the hydrolyzedtitanated support and drying the hydrolyzed titanated support by heatingto a temperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature in the range of from about 50° C. to about200° C. for a time period of from about 30 minutes to about 6 hours toform a hydrolyzed pre-catalyst; f) contacting, to form a pre-catalyst, achromium-containing compound and at least one material selected from thegroup consisting of the silica support, the dried support, the titanatedsupport, the dried titanated support, the mixture comprising thehydrolyzed titanated support, and the hydrolyzed pre-catalyst; and g)calcining the pre-catalyst by heating to a temperature in a range offrom about 400° C. to about 1000° C. and maintaining the temperature inthe range of from about 400° C. to about 1000° C. for a time period offrom about 1 minute to about 24 hours to form the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising a)drying a chrominated-silica support by heating to a temperature in arange of from about 150° C. to about 250° C. and maintaining thetemperature in the range of from about 150° C. to about 250° C. for atime period of from about 1 hour to about 24 hours to form a driedchrominated-silica support; b) contacting the dried chrominated-silicasupport and a titanium(IV) alkoxide to form a metalized support; c)heating the metalized support to a temperature in a range of from about50° C. to about 200° C. and maintaining the temperature in the range offrom about 50° C. to about 200° C. while contacting the metalizedsupport and a gas-phase solution material for a time period of fromabout 2 hours to about 48 hours; d) ceasing contacting of the metalizedsupport and the gas-phase solution to provide a hydrolyzed metalizedsupport having a temperature in a range of from about 50° C. to about200° C.; e) maintaining the temperature of the hydrolyzed metalizedsupport in the range of from about 50° C. to about 200° C. for a timeperiod of from about 30 minutes to about 6 hours to form a pre-catalyst;and f) calcining the pre-catalyst by heating to a temperature in a rangeof from about 400° C. to about 1000° C. and maintaining the temperaturein the range of from about 400° C. to about 1000° C. for a time periodof from about 1 minute to about 24 hours to form the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising a)drying a silica support by heating to a temperature in a range of fromabout 150° C. to about 250° C. and maintaining the temperature in therange of from about 150° C. to about 250° C. for a time period of fromabout 1 hour to about 24 hours to form a dried support; b) contactingthe dried support and a titanium(IV) alkoxide to form a titanatedsupport; c) heating the titanated support to a temperature in a range offrom about 50° C. to about 200° C. and maintaining the temperature inthe range of from about 50° C. to about 200° C. while contacting thetitanated support and a gas-phase solution for a time period of fromabout 2 hours to about 48 hours; d) ceasing contacting of the titanatedsupport and the gas-phase solution to provide a hydrolyzed supporthaving a temperature in a range of from about 50° C. to about 200° C.;e) maintaining the temperature in the range of from about 50° C. toabout 200° C. for a time period of from about 30 minutes to about 6hours to form a hydrolyzed pre-catalyst; f) contacting, to form apre-catalyst, a chromium-containing compound and at least one materialselected from the group consisting of the silica support, the driedsupport, the titanated support, the hydrolyzed support, and thehydrolyzed pre-catalyst; and g) calcining the pre-catalyst by heating toa temperature in a range of from about 400° C. to about 1000° C. andmaintaining the temperature in the range of from about 400° C. to about1000° C. for a time period of from about 1 minute to about 24 hours toform the catalyst.

BRIEF DESCRIPTION OF THE FIGURE

The following FIGURE forms part of the present specification and isincluded to further demonstrate certain aspects of the presentdisclosure. The subject matter of the present disclosure may be betterunderstood by reference to the FIGURE in combination with the detaileddescription of specific aspects presented herein.

The FIGURE illustrates a reaction of a silica support with Ti(OiPr)₄.

DETAILED DESCRIPTION

The present disclosure encompasses olefin polymerization catalysts,methods of preparing olefin polymerization catalysts, and methods ofutilizing olefin polymerization catalysts. In an aspect, a method of thepresent disclosure comprises contacting a silica support or achrominated-silica support (i.e., support), with titanium to produce aCr/Si—Ti catalyst. The methodologies disclosed herein contemplateapplication of an alkaline treatment (e.g., via contact with anitrogen-containing compound) during preparation of the Cr/Si—Ticatalyst to facilitate the association of titanium with the support. Themethodologies further contemplate that application of the alkalinetreatment may reduce the emissions of highly reactive volatile organiccompounds created during production the Cr/Si—Ti catalyst. While theseaspects may be disclosed under a particular heading, the heading doesnot limit the disclosure found therein. Additionally, the variousaspects and embodiments disclosed herein can be combined in any manner.

The methodologies disclosed herein contemplate application of analkaline treatment, for example via contact with a nitrogen-containingcompound. In an aspect, a method of preparation of an olefinpolymerization catalyst disclosed herein comprises utilization of anaqueous alkaline solution comprising the nitrogen-containing compound.In a particular aspect, the aqueous alkaline solution comprises waterand a nitrogen-containing compound. In some aspects, the aqueousalkaline solution optionally comprises a co-solvent.

Water suitable for use in the aqueous alkaline solution may be deionizedwater, distilled water, filtered water, or a combination thereof.

In an aspect, an aqueous alkaline solution of the present disclosurecomprises a nitrogen-containing compound. The nitrogen-containingcompound may be any nitrogen-containing compound suitable for providingeffective titanation of the olefin polymerization catalyst. In a furtheraspect, the nitrogen-containing compound may have Structure 1, Structure2, Structure 3, Structure 4, or a combination thereof.

-   -   N(R¹)₃ N(R²)₄OH N(R³)₂OH    -   Structure 1 Structure 2 Structure 3

R¹, R², R³, R⁴, R⁵, x, y, and z within a nitrogen-containing compoundutilized as described herein are independent elements of thenitrogen-containing compound structure in which they are present and areindependently described herein. The independent descriptions of R¹, R²,R³, R⁴, R⁵, x, y, and/or z provided herein can be utilized withoutlimitation, and in any combination, to further describe anynitrogen-containing compound structure which comprises an R¹, R², R³,R⁴, R⁵, x, y, and/or z

Generally, R¹, R², R³, R⁴, and/or R⁵ of a respective nitrogen-containingcompound which has an R¹, R², R³, R⁴, and/or R⁵ may each independentlybe hydrogen, an organyl group, a hydrocarbyl group, or an aryl group. Inan aspect, R¹, R², R³, R⁴, and/or R⁵ may each independently be a C₁ toC₃₀ organyl group; alternatively, a C₁ to C₁₂ organyl group; oralternatively, a C₁ to C₆ organyl group. In a further aspect, R¹, R²,R³, R⁴, and/or R⁵ may each independently be a C₁ to C₃₀ hydrocarbylgroup; alternatively, a C₁ to C₁₂ hydrocarbyl group; or alternatively, aC₁ to C₆ hydrocarbyl group. In yet other aspects, R¹, R², R³, R⁴, and/orR⁵ may each independently be a C₆ to C₃₀ aryl group; or alternatively, aC₆ to C₁₂ aryl group. In a further aspect, any organyl group,hydrocarbyl group, or aryl group which may be used as R¹, R², R³, R⁴,and/or R⁵ within the nitrogen-containing compound of the presentdisclosure may be substituted or non-substituted. It will be understoodby one skilled in the art that the terms “alkyl”, “hydrocarbyl”,“organyl”, and “aryl” are used herein in accordance with the definitionsfrom the IUPAC Compendium of Chemical Terminology, 2^(nd) Ed (1997).

In a particular aspect, any substituted organyl group, substitutedhydrocarbyl group, or substituted aryl group which may be used as R¹,R², R³, R⁴, and/or R⁵ may contain one or more non-hydrogen substituents.The non-hydrogen substituents suitable for use herein may be a halogen,a C₁ to C₁₂ hydrocarbyl group, a C₁ to C₁₂ hydrocarboxy group, or acombination thereof. In an aspect, the halogen utilized as thenon-hydrogen substituent may be fluorine, chlorine, bromine, or iodine.Non-limiting examples of the C₁ to C₁₂ hydrocarboxy group suitable foruse herein include a methoxy group, an ethoxy group, a propoxy group, abutoxy group, a pentoxy group, a hexoxy group, a phenoxy group, a toloxygroup, a xyloxy group, a trimethylphenoxy group, and a benzoxy group.

In still another aspect, a nitrogen-containing compound of the presentdisclosure having Structure 1 comprises three R¹ groups wherein each ofthe three R¹ groups may have independent values. In an aspect, anitrogen-containing compound having Structure 2 comprises four R² groupswherein each of the four R² groups may have independent values. In yet afurther aspect, a nitrogen-containing compound having Structure 3comprises two R³ groups wherein each of the two R³ groups may haveindependent values. In a further aspect, a nitrogen-containing compoundhaving Structure 4 comprises two R⁴ groups wherein each of the two R⁴groups may have independent values.

In an aspect, a nitrogen-containing compound suitable for use in thepresent disclosure may be an amide, an amidine, an amine, a diamine, atriamine, an amino acid, an ammonium hydroxide, a formamide, ahydrazine, a hydroxylamine, an imidazole, a piperazine, a piperidine, apyrazine, a pyrazole, a pyridine, a pyrimidine, a pyrrole, a urea, or acombination thereof. In a further aspect, the amide, the amidine, theamine, the diamine, the triamine, the amino acid, the ammoniumhydroxide, the formamide, the hydrazine, the hydroxylamine, theimidazole, the piperazine, the piperidine, the pyrazine, the pyrazole,the pyridine, the pyrimidine, the pyrrole, and/or the urea used as thenitrogen-containing compound may contain one or more substituent groups.In an aspect, any substituent group contained within anynitrogen-containing compound of the present disclosure may be a halogen,a C₁ to C₁₂ organyl group, a C₁ to C₁₂ hydrocarbyl group, a C₁ to C₁₂hydrocarboxy group, or a combination thereof. The halogen utilized asthe substituent group of any aspect disclosed herein may be fluorine,chlorine, bromine, or iodine. Non-limiting examples of the C₁ to C₁₂hydrocarboxy group suitable for use as the substituent group include amethoxy group, an ethoxy group, a propoxy group, a butoxy group, apentoxy group, a hexoxy group, a phenoxy group, a toloxy group, a xyloxygroup, a trimethylphenoxy group, and a benzoxy group.

In a further aspect, non-limiting examples of specificnitrogen-containing compounds suitable for use in the present disclosureinclude ammonia, ammonium hydroxide, tetraethylammonium hydroxide,tetramethylammonium hydroxide, hydrazine, hydroxylamine, trimethylamine, triethyl amine, acetamide, creatine,1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5-diazabicyclo[4.3.0]non-5-ene(DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU),N,N-diisopropylethylamine (DIPEA), dimethyl carbamate, formamide, methylformamide, dimethyl formamide, dimethyl glycine, 1,4-dimethylpiperazine(DMP), 1,3-dimethyl urea, imidazole, piperazine, piperidine, pyrazine,pyrazole, pyridine, pyrimidine, pyrrole, tetramethylethylenediamine(TMEDA), triazine, 1,3,5-triazacyclohexane,1,3,5-trimethyl-1,3,5-triazacyclohexane (TMTAC), or a combinationthereof.

In yet a further aspect, an aqueous alkaline solution of the presentdisclosure may optionally comprise a co-solvent. In an aspect, theco-solvent suitable for use herein may be an organic solvent such as analcohol, an ester, a ketone, or a combination thereof. Non-limitingexamples of alcohols suitable for use as the co-solvent includemethanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or acombination thereof. Non-limiting examples of esters suitable for use asthe co-solvent include ethyl acetate, propyl acetate, butyl acetate,isobutyl isobutyrate, methyl lactate, ethyl lactate, or a combinationthereof. Non-limiting examples of ketones suitable for use as theco-solvent include acetone, ethyl methyl ketone, methyl isobutyl ketone,or a combination thereof.

In an aspect, an amount of a nitrogen-containing compound present in theaqueous alkaline solution may be in a range of from about 1 wt. % toabout 50 wt. %; alternatively, from about 3 wt. % to about 20 wt. %; oralternatively, from about 4 wt. % to about 10 wt. % based upon the totalweight of the aqueous alkaline solution. In aspects where the aqueousalkaline solution comprises a co-solvent, a volumetric ratio ofco-solvent to water may be in a range of from about 1:20 to about 20:1;alternatively, from about 1:10 to about 10:1; alternatively, from about1:5 to about 5:1; or alternatively, from about 1:2 to about 2:1. Theremainder of the aqueous alkaline solution comprises water as disclosedherein.

In a still further aspect, a method of preparation of an olefinpolymerization catalyst disclosed herein contemplates application of analkaline treatment, for example via utilization of a gas-phase mixturecomprising a nitrogen containing compound. In an aspect, the gas-phasemixture comprises a vapor associated with a basic liquid (e.g., a vaporin equilibrium with the basic liquid). In a particular aspect, the basicliquid comprises an aqueous solution of a nitrogen-containing compounddisclosed herein. In a further aspect, the basic liquid comprises analcohol, non-limiting examples of which include methanol, ethanol,n-propanol, isopropanol, or a combination thereof.

In an aspect, an amount of nitrogen-containing compound in the aqueoussolution is from about 3 wt. % to about 20 wt. % based upon the totalweight of the aqueous solution. In a further aspect the basic liquidcomprises a volumetric ratio of the aqueous solution to the alcohol in arange of from 10:1 to about 1:10; alternatively, from about 4:1 to about1:4; alternatively, from about 7:3 to about 3:7; or alternatively, fromabout 1.2:1 to about 1:1.2.

In a particular aspect, the basic liquid and the vapor associated withthe basic liquid may each independently have a temperature in a range offrom about 120° C. to about 200° C.; or alternatively, from about 150°C. to about 170° C.

In a still further aspect, a gas-phase mixture suitable for use hereincomprises a vapor associated with a basic liquid comprising MeOH and anaqueous solution of NH₄OH. In a further aspect the gas-phase mixturecomprises ammonia, methanol, water, or a combination thereof. In anaspect, an amount of NH₄OH present in the aqueous solution may be in arange of from about 2 wt. % to about 10 wt. % based upon the totalweight of the aqueous solution. In a further aspect, the basic liquidcomprises a volumetric ratio of MeOH to the aqueous solution in a rangeof from 10:1 to about 1:10; or alternatively, from about 7:3 to about3:7. In a further aspect, the basic liquid and the vapor associated withthe basic liquid may each independently have a temperature in a range offrom about 150° C. to about 170° C.

In a particular aspect, an olefin polymerization catalyst of the presentdisclosure comprises titanium. The source of the titanium may be anytitanium-containing compound capable of providing effective titanationto the olefin polymerization catalyst. In a further aspect, thetitanium-containing compound comprises a tetravalent titanium (Ti(IV))compound or a trivalent titanium (Ti(III)) compound. The Ti(IV) compoundmay be any compound that comprises Ti(IV); alternatively, the Ti(IV)compound may be any compound that is able to release a Ti(IV) speciesupon dissolving into solution. The Ti(III) compound may be any compoundthat comprises Ti(III); alternatively, the Ti(III) compound may be anycompound that is able to release a Ti(III) species upon dissolving intosolution.

In an aspect, the titanium-containing compound suitable for use in thepresent disclosure comprises a Ti(IV) compound having at least onealkoxide group; or alternatively, at least two alkoxide groups. Ti(IV)compounds suitable for use in the present disclosure include, but arenot limited to, Ti(IV) compounds that have the general formulaTiO(OR⁶)₂, Ti(OR⁶)₂(acac)₂, Ti(OR⁶)₂(oxal), a combination thereofwherein R⁶ may be ethyl, isopropyl, n-propyl, isobutyl, n-butyl, or acombination thereof; “acac” is acetylacetonate; and “oxal” is oxalate.Alternatively, the titanium-containing compound comprises a titanium(IV)alkoxide. In an aspect, the titanium(IV) alkoxide may be titanium(IV)ethoxide, titanium(IV) isopropoxide, titanium(IV) n-propoxide,titanium(IV) n-butoxide, titanium(IV) 2-ethylhexoxide, or a combinationthereof. In a particular aspect, the titanium-containing compound may betitanium(IV) isopropoxide.

In yet another aspect, the titanium-containing compound suitable for usein the present disclosure may comprise a titanium(IV) halide,non-limiting examples of which include titanium(IV) chloride andtitanium(IV) bromide.

An amount of titanium present in an olefin polymerization catalyst mayrange from about 0.01 wt. % to about 10 wt. %; alternatively, from about0.5 wt. % to about 5 wt. %; alternatively, from about 1 wt. % to about 4wt. %; or alternatively, from about 2 wt. % to about 4 wt. %. titaniumbased upon a total weight of the olefin polymerization catalyst. Inanother aspect, the amount of titanium present in the olefinpolymerization catalyst may range from about 1 wt. % to about 5 wt. %titanium based upon the total weight of the olefin polymerizationcatalyst. Herein, a titanium percentage refers to a weight percent (wt.%), of titanium associated with the olefin polymerization catalyst basedupon the total weight of the olefin polymerization catalyst aftercompletion of all processing steps (i.e., after activation viacalcination).

In a further aspect, a weight ratio of the amount of aqueous alkalinesolution to the amount of titanium-containing compound utilized toprepare an olefin polymerization catalyst disclosed herein may be in arange of from about 100:1 to about 1:1; or alternatively, from about30:1 to about 3:1. Alternatively, an amount of aqueous alkaline solutionutilized is sufficient to provide an equivalent molar ratio ofnitrogen-containing compound to titanium-containing compound in a rangeof from about 100:1 to about 1:2; alternatively, from about 50:1 toabout 1:1; or alternatively, from about 20:1 to about 3:1.

In another aspect, an olefin polymerization catalyst of the presentdisclosure comprises a silica support. The silica support may be anysilica support suitable for preparation of the olefin polymerizationcatalyst as disclosed herein. The silica support may have a surface areaand a pore volume effective to provide for the production of an activeolefin polymerization catalyst. In an aspect of the present disclosure,the silica support possesses a surface area in a range of from about 100m²/gram to about 1000 m²/gram; alternatively, from about 250 m²/gram toabout 1000 m²/gram; alternatively, from about 250 m²/gram to about 700m²/gram; alternatively, from about 250 m²/gram to about 600 m²/gram; oralternatively, greater than about 250 m²/gram. The silica support may befurther characterized by a pore volume of greater than about 0.9cm³/gram; alternatively, greater than about 1.0 cm³/gram; oralternatively, greater than about 1.5 cm³/gram. In an aspect of thepresent disclosure, the silica support is characterized by a pore volumein a range of from about 1.0 cm³/gram to about 2.5 cm³/gram. The silicasupport may be further characterized by an average particle size in arange of from about 10 microns to about 500 microns; alternatively,about 25 microns to about 300 microns; or alternatively, about 40microns to about 150 microns. Generally, an average pore size of thesilica support may be in a range of from about 10 Angstroms to about1000 Angstroms. In one aspect of the present disclosure, the averagepore size of the silica support is in a range of from about 50 Angstromsto about 500 Angstroms; or alternatively, from about 75 Angstroms toabout 350 Angstroms.

The silica support suitable for use in the present disclosure maycontain greater than about 50 wt. % silica; alternatively, greater thanabout 80 wt. % silica; or alternatively, greater than about 95 wt. %silica based upon the total weight of the silica support. The silicasupport may be prepared using any suitable method, e.g., the silicasupport may be prepared by hydrolyzing tetrachlorosilane (SiCl₄), withwater or by contacting sodium silicate and a mineral acid. The silicasupport may include additional components that do not adversely affectthe catalyst, such as zirconia, alumina, thoria, magnesia, fluoride,sulfate, phosphate, or a combination thereof. Non-limiting examples ofsilica supports suitable for use in this disclosure include ES70, whichis a silica support material with a surface area of 300 m²/gram and apore volume of 1.6 cm³/gram, that is commercially available from PQCorporation and V398400, which is a silica support material that iscommercially available from Evonik.

In a particular aspect of the present disclosure, a silica supportsuitable for use in the present disclosure comprises chromium. Thesilica support comprising chromium may be termed a chrominated-silicasupport. In another aspect, the chrominated-silica support comprises thecharacteristics disclosed herein for the silica support whileadditionally containing chromium. A non-limiting example of thechrominated-silica support is HW30A, which is a chrominated-silicasupport material that is commercially available from W. R. Grace andCompany.

The silica support may be present in the olefin polymerization catalystin an amount in a range of from about 50 wt. % to about 99 wt. %; oralternatively, from about 80 wt. % to about 99 wt. %. Herein a silicasupport percentage refers to a weight percent (wt. %), of the silicasupport associated with the olefin polymerization catalyst based upon atotal weight of the olefin polymerization catalyst after completion ofall processing steps (i.e., after activation via calcination).

In a still further aspect, an olefin polymerization catalyst of thepresent disclosure comprises chromium. The source of chromium may be anychromium-containing compound capable of providing a sufficient amount ofchromium to the olefin polymerization catalyst. In an aspect, thechromium-containing compound may be a water-soluble chromium compound ora hydrocarbon-soluble chromium compound. Examples of water-solublechromium compounds include chromium trioxide, chromium acetate, chromiumnitrate, or a combination thereof. Examples of hydrocarbon-solublechromium compounds include tertiary butyl chromate, biscyclopentadienylchromium(II), chromium(III) acetylacetonate, or a combination thereof.In one aspect of the present disclosure, the chromium-containingcompound may be a chromium(II) compound, a chromium(III) compound, or acombination thereof. Suitable chromium(III) compounds include, but arenot limited to, chromium(III) carboxylates, chromium(III) naphthenates,chromium(III) halides, chromium(III) sulfates, chromium(III) nitrates,chromium(III) dionates, or a combination thereof. Specific chromium(III)compounds include, but are not limited to, chromium(III) sulfate,chromium(III) chloride, chromium(III) nitrate, chromium(III) bromide,chromium(III) acetylacetonate, and chromium(III) acetate. Suitablechromium(II) compounds include, but are not limited to, chromium(II)chloride, chromium(II) bromide, chromium(II) iodide, chromium(II)sulfate, chromium(II) acetate, or a combination thereof.

An amount of chromium present in an olefin polymerization catalyst maybe in a range of from about 0.01 wt. % to about 10 wt. %; alternatively,from about 0.5 wt. % to about 5 wt. %; alternatively, from about 1 wt. %to about 4 wt. %; or alternatively, from about 2 wt. % to about 4 wt. %chromium based upon a total weight of the olefin polymerizationcatalyst. In another aspect, the amount of chromium present in theolefin polymerization catalyst may be in a range of from about 1 wt. %to about 5 wt. % chromium based upon the total weight of the olefinpolymerization catalyst. Herein, a chromium percentage refers to aweight percent (wt. %), of chromium associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination).

In yet a further aspect, one or more components of an olefinpolymerization catalyst of the present disclosure may be contacted inthe presence of a solvent. In a particular aspect, the solvent suitablefor use may be a hydrocarbon, an alcohol, an organic solvent, an aqueoussolvent, or a combination thereof. In an aspect, the hydrocarbonsuitable for use as the solvent may be an aliphatic hydrocarbon, ahalogenated aliphatic hydrocarbon, an aromatic hydrocarbon, ahalogenated aromatic hydrocarbon, or a combination thereof. Non-limitingexamples of the hydrocarbon suitable for use as the solvent includebenzene, chloroform, carbon tetrachloride, chlorobenzene,dichlorobenzene, dichloroethane, ethylbenzene, hexane, heptane,methylene chloride, octane, trichloroethane, toluene, xylenes, or acombination thereof. In a further aspect, a hydrocarbon solvent suitablefor use in the present disclosure comprises heptane. Non-limitingexamples of alcohols suitable for use as the solvent include methanol,ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol,hexanol, cyclohexanol, heptanol, octanol, benzyl alcohol, phenol, or acombination thereof. In a further aspect, the organic solvent suitablefor use in the present disclosure may be an ester, a ketone, or acombination thereof. Non-limiting examples of esters suitable for use asthe solvent include ethyl acetate, propyl acetate, butyl acetate,isobutyl isobutyrate, methyl lactate, ethyl lactate, or a combinationthereof. Non-limiting examples of ketones suitable for use as thesolvent include acetone, ethyl methyl ketone, methyl isobutyl ketone, ora combination thereof.

In an aspect of the present disclosure the catalyst components disclosedherein may be contacted in any order or fashion deemed suitable to oneskilled in the art with the aid of the present disclosure to produce anolefin polymerization catalyst having the characteristics disclosedherein.

In an aspect, a method for preparation of an olefin polymerizationcatalyst comprises drying a silica support prior to contact with anyother component of the olefin polymerization catalyst to form a driedsupport. The silica support may be dried by heating to a temperature ina range of from about 110° C. to about 500° C.; alternatively, fromabout 150° C. to about 300° C.; or alternatively, from about 150° C. toabout 250° C. The method further comprises maintaining the temperatureof the silica support in the range of from about 110° C. to about 500°C.; alternatively, from about 150° C. to about 300° C.; oralternatively, from about 150° C. to about 250° C. for a time period offrom about 1 hour to about 24 hours; alternatively, from about 5 hoursto about 24 hours; or alternatively, from about 5 hours to about 12hours to form the dried support. Drying of the silica support may beconducted in an inert atmosphere (e.g., under vacuum, He, Ar, or N₂gas). A dryness of the dried support may be measured as a loss in weightupon drying at a temperature of about 250° C. for a time period of fromabout 1 hour to about 12 hours. In an aspect, the loss in weight upondrying of the dried support is less than about 3 wt. %; alternatively,less than about 2 wt. %; or alternatively, less than about 1 wt. %.

The method may further comprise contacting the dried support and atitanium-containing compound of the type disclosed herein to form atitanated support. The titanated support may be dried by heating to atemperature in a range of from about 50° C. to about 500° C.;alternatively, from about 50° C. to about 200° C.; or alternatively,from about 80° C. to about 150° C. The method further comprisesmaintaining the temperature of the titanated support in the range offrom about 50° C. to about 500° C.; alternatively, from about 50° C. toabout 200° C.; or alternatively, from about 80° C. to about 150° C. fora time period of from about 30 minutes to about 24 hours; alternatively,from about 30 minutes to about 6 hours; or alternatively, from about 2hours to about 6 hours to form a dried titanated support. The method mayfurther comprise contacting the dried titanated support and an aqueousalkaline solution of the type disclosed herein to form a mixturecomprising a hydrolyzed titanated support. In yet another aspect, thedried titanated support and the aqueous alkaline solution may becontacted for a time period of from about 1 minute to about 24 hours;alternatively, from about 10 minutes to about 6 hours; or alternatively,from about 1 hour to about 3 hours. In an aspect, the mixture formed bycontacting the dried titanated support and the aqueous alkaline solutionmay be a slurry, a suspension, a colloid, or a combination thereof. Themethod further comprises removing the hydrolyzed titanated support fromthe mixture comprising the hydrolyzed titanated support. In an aspect,the hydrolyzed titanated support may be removed by any suitablemethodology, non-limiting examples of which include filtration,centrifugation, gravimetric settling, membrane filtration, or acombination thereof. The method may further comprise drying thehydrolyzed titanated support by heating to a temperature in a range offrom about 35° C. to about 500° C.; alternatively, from about 50° C. toabout 200° C.; or alternatively, from about 75° C. to about 125° C. Themethod further comprises maintaining the temperature of the hydrolyzedtitanated support in the range of from about 35° C. to about 500° C.;alternatively, from about 50° C. to about 200° C.; or alternatively,from about 75° C. to about 125° C. for a time period of from about 5minutes to about 24 hours; alternatively, from about 30 minutes to about12 hours; alternatively, from about 30 minutes to about 6 hours; oralternatively, from about 1 hour to about 3 hours to form a hydrolyzedpre-catalyst.

In a further aspect, a method for preparation of an olefinpolymerization catalyst comprises preparing a dried chrominated-silicasupport. The method may comprise contacting a chromium-containingcompound and a silica support, both of the type disclosed herein, toform a chrominated-silica support that is subsequently dried by heatingto a temperature in a range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. The method may further comprisemaintaining the temperature of the chrominated-silica support in therange of from about 110° C. to about 500° C.; alternatively, from about150° C. to about 300° C.; or alternatively, from about 150° C. to about250° C. for a time period of from about 30 minutes to about 24 hours;alternatively, from about 30 minutes to about 6 hours; or alternatively,from about 2 hours to about 6 hours to form the dried chrominated-silicasupport. In an alternative aspect, the chromium-containing compound anda dried support may be contacted to form the dried chrominated-silicasupport. In a further alternative aspect, a chrominated-silica supportas disclosed herein (e.g., HA30W), is dried by heating to a temperaturein a range of from about 110° C. to about 500° C.; alternatively, fromabout 150° C. to about 300° C.; or alternatively, from about 150° C. toabout 250° C. and maintaining the temperature of the chrominated-silicasupport in the range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. for a time period of from about 30minutes to about 24 hours; alternatively, from about 30 minutes to about6 hours; or alternatively, from about 2 hours to about 6 hours to formthe dried chrominated-silica support. Drying of the chrominated-silicasupport may be conducted in an inert atmosphere (e.g., under vacuum, He,Ar, or N₂ gas). A dryness of the dried chrominated-silica support may bemeasured as a loss in weight upon drying at a temperature of about 250°C. for a time period of from about 1 hour to about 12 hours. In anaspect, the loss in weight upon drying of the dried chrominated-silicasupport is less than about 3 wt. %; alternatively, less than about 2 wt.%; or alternatively, less than about 1 wt. %.

The method further comprises contacting the dried chrominated-silicasupport and a titanium-containing compound of the type disclosed hereinto form a metalized support that may subsequently be dried by heating toa temperature in a range of from about 50° C. to about 500° C.;alternatively, from about 50° C. to about 200° C.; or alternatively,from about 80° C. to about 150° C. The method further comprisesmaintaining the temperature of the metalized support in the range offrom about 50° C. to about 500° C.; alternatively, from about 50° C. toabout 200° C.; or alternatively, from about 80° C. to about 150° C. fora time period of from about 30 minutes to about 24 hours; alternatively,from about 30 minutes to about 6 hours; or alternatively, from about 2hours to about 6 hours to form a dried metalized support. In an aspect,the method may further comprise contacting the dried metalized supportand an aqueous alkaline solution of the type disclosed herein to form amixture comprising a hydrolyzed metalized support. In an aspect, thedried metalized support and the aqueous alkaline solution may becontacted for a time period of from about 1 minute to about 24 hours andthe mixture formed thereby may be a slurry, a suspension, a colloid, ora combination thereof. The method further comprises removing thehydrolyzed metalized support from the mixture comprising the hydrolyzedmetalized support by any suitable methodology, non-limiting examples ofwhich include filtration, centrifugation, gravimetric settling, membranefiltration, or a combination thereof. The method may further comprisedrying the hydrolyzed metalized support by heating to a temperature in arange of from about 35° C. to about 500° C.; alternatively, from about50° C. to about 200° C.; or alternatively, from about 75° C. to about125° C. and maintaining the temperature of the hydrolyzed metalizedsupport in the range of from about 35° C. to about 500° C.;alternatively, from about 50° C. to about 200° C.; or alternatively,from about 75° C. to about 125° C. for a time period of from about 5minutes to about 24 hours; alternatively, from about 30 minutes to about12 hours; alternatively, from about 30 minutes to about 6 hours; oralternatively, from about 1 hour to about 3 hours to form apre-catalyst.

In an alternative aspect, a method for preparation of an olefinpolymerization catalyst comprises contacting a chromium-containingcompound and a titanated support to form a metalized support that issubsequently dried to form a dried metalized support. The driedmetalized support may be contacted with an aqueous alkaline solution toform a mixture comprising a hydrolyzed metalized support. The hydrolyzedmetalized support may be removed from the mixture comprising thehydrolyzed metalized support and dried to form a pre-catalyst.

In a further alternative aspect, the chromium-containing compound and adried titanated support are contacted to form the dried metalizedsupport that is subsequently contacted with the aqueous alkalinesolution to form a mixture comprising the hydrolyzed metalized support.The hydrolyzed metalized support may be removed from the mixturecomprising the hydrolyzed metalized support and dried to form thepre-catalyst.

In yet a further alternative aspect, the chromium-containing compoundand a mixture comprising a hydrolyzed titanated support prepared withthe aqueous alkaline solution are contacted to form a mixture comprisinga hydrolyzed metalized support. The hydrolyzed metalized support may beremoved from the mixture comprising the hydrolyzed metalized support anddried to form the pre-catalyst.

In yet another alternative aspect, the chromium-containing compound anda hydrolyzed pre-catalyst prepared with the aqueous alkaline solutionare contacted to form the pre-catalyst.

In a particular aspect, a method for preparation of an olefinpolymerization catalyst comprises drying a silica support prior tocontact with any other component of the olefin polymerization catalystto form a dried support. The silica support may be dried by heating to atemperature in a range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. The method further comprisesmaintaining the temperature of the silica support in the range of fromabout 110° C. to about 500° C.; alternatively, from about 150° C. toabout 300° C.; or alternatively, from about 150° C. to about 250° C. fora time period of from about 1 hour to about 24 hours; alternatively,from about 5 hours to about 24 hours; or alternatively, from about 5hours to about 12 hours to form the dried support. Drying of the silicasupport may be conducted in an inert atmosphere (e.g., under vacuum, He,Ar, or N₂ gas). A dryness of the dried support may be measured as a lossin weight upon drying at a temperature of about 250° C. for a timeperiod of from about 1 hour to about 12 hours. In an aspect, the loss inweight upon drying of the dried support is less than about 3 wt. %;alternatively, less than about 2 wt. %; or alternatively, less thanabout 1 wt. %.

The method further comprises contacting the dried support and atitanium-containing compound of the type disclosed herein to form amixture comprising a titanated support. In an aspect, the mixturecomprising the titanated support comprises a solvent suitable for use asdisclosed herein (e.g., heptane). The method may further compriseheating the mixture comprising the titanated support to a temperature ina range of from about 35° C. to about 500° C.; alternatively, from about50° C. to about 200° C.; or alternatively, from about 75° C. to about125° C. and maintaining the temperature in the range of from about 35°C. to about 500° C.; alternatively, from about 50° C. to about 200° C.;or alternatively, from about 75° C. to about 125° C. The mixturecomprising the titanated support during heating may be contacted with agas-phase mixture for a time period of from about 30 minutes to about 48hours; alternatively, from about 1 hour to about 24 hours; oralternatively, from about 2 hours to about 8 hours. In an aspect,contacting the mixture comprising the titanated support and thegas-phase mixture comprises maintaining a flow of the gas-phase mixturethrough the mixture comprising the titanated support. In a non-limitingexample, a stream of the gas-phase mixture may be bubbled through themixture comprising the titanated support. The method further comprisesceasing contacting of the mixture comprising the titanated support andthe gas-phase mixture to provide a mixture comprising a hydrolyzedsupport having a temperature in a range of from about 35° C. to about500° C.; alternatively, from about 50° C. to about 200° C.; oralternatively, from about 75° C. to about 125° C. The method furthercomprises drying the hydrolyzed support by maintaining the temperatureof the hydrolyzed support in a range of from about 35° C. to about 500°C.; alternatively, from about 50° C. to about 200° C.; or alternatively,from about 75° C. to about 125° C. to form a hydrolyzed pre-catalyst.

In a still further aspect, a method for preparation of an olefinpolymerization catalyst comprises preparing a dried chrominated-silicasupport. The method may comprise contacting a chromium-containingcompound and a silica support, both of the type disclosed herein, toform a chrominated-silica support that is subsequently dried by heatingto a temperature in a range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. The method may further comprisemaintaining the temperature of the chrominated-silica support in therange of from about 110° C. to about 500° C.; alternatively, from about150° C. to about 300° C.; or alternatively, from about 150° C. to about250° C. for a time period of from about 30 minutes to about 24 hours;alternatively, from about 30 minutes to about 6 hours; or alternatively,from about 2 hours to about 6 hours to form the dried chrominated-silicasupport. In an alternative aspect, the chromium-containing compound anda dried support may be contacted to form the dried chrominated-silicasupport. In a further alternative aspect, a chrominated-silica supportas disclosed herein (e.g., HA30W), is dried by heating to a temperaturein a range of from about 110° C. to about 500° C.; alternatively, fromabout 150° C. to about 300° C.; or alternatively, from about 150° C. toabout 250° C. and maintaining the temperature of the chrominated-silicasupport in the range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. for a time period of from about 30minutes to about 24 hours; alternatively, from about 30 minutes to about6 hours; or alternatively, from about 2 hours to about 6 hours to formthe dried chrominated-silica support. Drying of the chrominated-silicasupport may be conducted in an inert atmosphere (e.g., under vacuum, He,Ar, or N₂ gas). A dryness of the dried chrominated-silica support may bemeasured as a loss in weight upon drying at a temperature of about 250°C. for a time period of from about 1 hour to about 12 hours. In anaspect, the loss in weight upon drying of the dried chrominated-silicasupport is less than about 3 wt. %; alternatively, less than about 2 wt.%; or alternatively, less than about 1 wt. %.

The method further comprises contacting the dried chrominated-silicasupport and a titanium-containing compound of the type disclosed hereinto form a mixture comprising a metalized support. In a further aspect,the mixture comprising the metalized support comprises a solventsuitable for use as disclosed herein (e.g., heptane). The method mayfurther comprise heating the mixture comprising the metalized support toa temperature in a range of from about 35° C. to about 500° C.;alternatively, from about 50° C. to about 200° C.; or alternatively,from about 75° C. to about 125° C. and maintaining the temperature inthe range of from about 35° C. to about 500° C.; alternatively, fromabout 50° C. to about 200° C.; or alternatively, from about 75° C. toabout 125° C. The mixture comprising the metalized support duringheating may be contacted with a gas-phase mixture for a time period offrom about 30 minutes to about 48 hours; alternatively, from about 1hour to about 24 hours; or alternatively, from about 2 hours to about 8hours. In a further aspect, contacting the mixture comprising themetalized support and the gas-phase mixture comprises maintaining a flowof the gas-phase mixture through the mixture comprising the metalizedsupport. In a non-limiting example, a stream of the gas-phase mixturemay be bubbled through the mixture comprising the metalized support. Themethod further comprises ceasing contacting of the mixture comprisingthe metalized support and the gas-phase mixture to provide a mixturecomprising a hydrolyzed metalized support having a temperature in arange of from about 35° C. to about 500° C.; alternatively, from about50° C. to about 200° C.; or alternatively, from about 75° C. to about125° C. The method further comprises drying the hydrolyzed metalizedsupport by maintaining the temperature of the hydrolyzed metalizedsupport in a range of from about 35° C. to about 500° C.; alternatively,from about 50° C. to about 200° C.; or alternatively, from about 75° C.to about 125° C. to form a pre-catalyst.

In an alternative aspect, a method for preparation of an olefinpolymerization catalyst comprises contacting a chromium-containingcompound and a mixture comprising a titanated support to form a mixturecomprising a metalized support. In an aspect, the mixture comprising thetitanated support comprises a solvent suitable for use as disclosedherein (e.g., heptane). The mixture comprising the metalized support maybe heated and contacted with a gas-phase mixture to provide a mixturecomprising a hydrolyzed metalized support. The hydrolyzed metalizedsupport may be dried to form a pre-catalyst.

In a further alternative aspect, the chromium-containing compound and amixture comprising a hydrolyzed support prepared with the gas-phasemixture are contacted to form the mixture comprising the hydrolyzedmetalized support. In an aspect, the hydrolyzed metalized support may bedried to form the pre-catalyst.

In yet another alternative aspect, the chromium-containing compound anda hydrolyzed pre-catalyst prepared with the gas-phase mixture arecontacted to form the pre-catalyst.

In a particular aspect, a method for preparation of an olefinpolymerization catalyst comprises drying a silica support prior tocontact with any other component of the olefin polymerization catalystto form a dried support. The silica support may be dried by heating to atemperature in a range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. The method further comprisesmaintaining the temperature of the silica support in the range of fromabout 110° C. to about 500° C.; alternatively, from about 150° C. toabout 300° C.; or alternatively, from about 150° C. to about 250° C. fora time period of from about 1 hour to about 24 hours; alternatively,from about 5 hours to about 24 hours; or alternatively, from about 5hours to about 12 hours to form the dried support. Drying of the silicasupport may be conducted in an inert atmosphere (e.g., under vacuum, He,Ar, or N₂ gas). A dryness of the dried support may be measured as a lossin weight upon drying at a temperature of about 250° C. for a timeperiod of from about 1 hour to about 12 hours. In an aspect, the loss inweight upon drying of the dried support is less than about 3 wt. %;alternatively, less than about 2 wt. %; or alternatively, less thanabout 1 wt. %.

The method further comprises contacting the dried support and atitanium-containing compound of the type disclosed herein to form amixture comprising a titanated support. In a further aspect, the mixturecomprising the titanated support comprises a solvent suitable for use asdisclosed herein (e.g., heptane). The method may further compriseheating the mixture comprising the titanated support to a temperature ina range of from about 35° C. to about 500° C.; alternatively, from about50° C. to about 200° C.; or alternatively, from about 75° C. to about125° C. and maintaining the temperature in the range of from about 35°C. to about 500° C.; alternatively, from about 50° C. to about 200° C.;or alternatively, from about 75° C. to about 125° C. The mixturecomprising the titanated support during heating may be contacted with anaqueous alkaline solution for a time period of from about 30 minutes toabout 48 hours; alternatively, from about 1 hour to about 24 hours; oralternatively, from about 2 hours to about 8 hours. In an aspect, theaqueous alkaline solution and the mixture comprising the titanatedsupport are insoluble and do not mix upon being contacted wherein beingcontacted comprises liquid/liquid extraction and optional agitation. Themethod further comprises ceasing contacting of the mixture comprisingthe titanated support and the aqueous alkaline solution (e.g.,separation of the mixture and the solution), to provide a mixturecomprising a hydrolyzed support having a temperature in a range of fromabout 35° C. to about 500° C.; alternatively, from about 50° C. to about200° C.; or alternatively, from about 75° C. to about 125° C. The methodfurther comprises drying the hydrolyzed support by maintaining thetemperature of the hydrolyzed support in a range of from about 35° C. toabout 500° C.; alternatively, from about 50° C. to about 200° C.; oralternatively, from about 75° C. to about 125° C. to form a hydrolyzedpre-catalyst.

In an aspect, a method for preparation of an olefin polymerizationcatalyst comprises preparing a dried chrominated-silica support. Themethod may comprise contacting a chromium-containing compound and asilica support, both of the type disclosed herein, to form achrominated-silica support that is subsequently dried by heating to atemperature in a range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. The method may further comprisemaintaining the temperature of the chrominated-silica support in therange of from about 110° C. to about 500° C.; alternatively, from about150° C. to about 300° C.; or alternatively, from about 150° C. to about250° C. for a time period of from about 30 minutes to about 24 hours;alternatively, from about 30 minutes to about 6 hours; or alternatively,from about 2 hours to about 6 hours to form the dried chrominated-silicasupport. In an alternative aspect, the chromium-containing compound anda dried support may be contacted to form the dried chrominated-silicasupport. In a further alternative aspect, a chrominated-silica supportas disclosed herein (e.g., HA30W), is dried by heating to a temperaturein a range of from about 110° C. to about 500° C.; alternatively, fromabout 150° C. to about 300° C.; or alternatively, from about 150° C. toabout 250° C. and maintaining the temperature of the chrominated-silicasupport in the range of from about 110° C. to about 500° C.;alternatively, from about 150° C. to about 300° C.; or alternatively,from about 150° C. to about 250° C. for a time period of from about 30minutes to about 24 hours; alternatively, from about 30 minutes to about6 hours; or alternatively, from about 2 hours to about 6 hours to formthe dried chrominated-silica support. Drying of the chrominated-silicasupport may be conducted in an inert atmosphere (e.g., under vacuum, He,Ar, or N₂ gas). A dryness of the dried chrominated-silica support may bemeasured as a loss in weight upon drying at a temperature of about 250°C. for a time period of from about 1 hour to about 12 hours. In anaspect, the loss in weight upon drying of the dried chrominated-silicasupport is less than about 3 wt. %; alternatively, less than about 2 wt.%; or alternatively, less than about 1 wt. %.

The method further comprises contacting the dried chrominated-silicasupport and a titanium-containing compound of the type disclosed hereinto form a mixture comprising a metalized support. In a further aspect,the mixture comprising the metalized support comprises a solventsuitable for use as disclosed herein (e.g., heptane). The method mayfurther comprise heating the mixture comprising the metalized support toa temperature in a range of from about 35° C. to about 500° C.;alternatively, from about 50° C. to about 200° C.; or alternatively,from about 75° C. to about 125° C. and maintaining the temperature inthe range of from about 35° C. to about 500° C.; alternatively, fromabout 50° C. to about 200° C.; or alternatively, from about 75° C. toabout 125° C. The mixture comprising the metalized support duringheating may be contacted with an aqueous alkaline solution for a timeperiod of from about 30 minutes to about 48 hours; alternatively, fromabout 1 hour to about 24 hours; or alternatively, from about 2 hours toabout 8 hours. In an aspect, the aqueous alkaline solution and themixture comprising the titanated support are insoluble and do not mixupon being contacted wherein being contacted comprises liquid/liquidextraction and optional agitation. The method further comprises ceasingcontacting of the mixture comprising the titanated support and theaqueous alkaline solution (e.g., separation of the mixture and thesolution), to provide a mixture comprising a hydrolyzed metalizedsupport having a temperature in a range of from about 35° C. to about500° C.; alternatively, from about 50° C. to about 200° C.; oralternatively, from about 75° C. to about 125° C. The method furthercomprises drying the hydrolyzed metalized support by maintaining thetemperature of the hydrolyzed metalized support in a range of from about35° C. to about 500° C.; alternatively, from about 50° C. to about 200°C.; or alternatively, from about 75° C. to about 125° C. to form apre-catalyst.

In an alternative aspect, a method for preparation of an olefinpolymerization catalyst comprises contacting a chromium-containingcompound and a mixture comprising a titanated support to form a mixturecomprising a metalized support. In an aspect, the mixture comprising thetitanated support comprises a solvent suitable for use as disclosedherein (e.g., heptane). The mixture comprising the metalized support maybe heated and contacted with an aqueous alkaline solution to provide amixture comprising a hydrolyzed metalized support. The hydrolyzedmetalized support may be dried to form a pre-catalyst.

In an alternative aspect, the chromium-containing compound and a mixturecomprising a hydrolyzed support prepared by liquid/liquid extractionwith an aqueous alkaline solution are contacted to form the mixturecomprising the hydrolyzed metalized support. The hydrolyzed metalizedsupport may be dried to form the pre-catalyst.

In another alternative aspect, the chromium-containing compound and ahydrolyzed pre-catalyst prepared by liquid/liquid extraction with anaqueous alkaline solution are contacted to form the pre-catalyst.

In any aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst further comprises activating apre-catalyst prepared as disclosed herein via a calcination step. Insome aspects, calcination of the pre-catalyst comprises heating thepre-catalyst in an oxidizing environment to produce the olefinpolymerization catalyst. For example, the pre-catalyst may be calcinedby heating the pre-catalyst in the presence of air to a temperature in arange of from about 400° C. to about 1000° C.; alternatively, from about500° C. to about 900° C.; or alternatively, from about 500° C. to about850° C. Calcination of the pre-catalyst may further comprise maintainingthe temperature of the pre-catalyst in the presence of air in the rangeof from about 400° C. to about 1000° C.; alternatively, from about 500°C. to about 900° C.; or alternatively, from about 500° C. to about 850°C. for a time period in a range of from about 1 minute to about 24hours; alternatively, from about 1 minute to about 12 hours;alternatively, from about 20 minutes to about 12 hours; alternatively,from about 1 hour to about 10 hours; alternatively, from about 3 hoursto about 10 hours; or alternatively, from about 3 hours to about 5 hoursto produce the olefin polymerization catalyst.

During catalyst production, materials such as highly reactive volatileorganic compounds (HRVOC), may be emitted. HRVOCs play a role in theformation of ozone in ozone nonattainment areas, i.e., areas that do notmeet the Environmental Protection Agency's air quality standards forground-level ozone. In an aspect of the present disclosure, an olefinpolymerization catalyst prepared as disclosed herein results in areduction in the level of HRVOCs produced during the olefinpolymerization catalyst preparation. For example, the HRVOCs maycomprise hydrocarbons, aromatic compounds, alcohols, ketones, orcombinations thereof. In an aspect of the present disclosure, the HRVOCscomprise alcohols and alkenes non-limiting examples of which includeethanol, propanol, butanol, ethylene, propylene, and butane.

The simplified reaction scheme in the FIGURE illustrates hydroxyl groupsupon the surface of a silica support and replacement of Si—O—H bondsamong the hydroxyl groups with Si—O—Ti bonds formed during a titanationreaction upon the support. The FIGURE also displays that one equivalentof Ti(OiPr)₄ can react with no more than two hydroxyl groups such that aresultant titanated support contains numerous isopropoxide (OiPr),groups bound in Ti—O-iPr bonds. The Ti—O-iPr bonds can remain intactthroughout the preparation of the catalyst until encountering theelevated temperatures used to activate the catalyst during calcination.Not wishing to be limited by theory, cleavage of the Ti—O-iPr bondsgenerates isopropanol and contributes to HRVOC emissions. In some cases,an isopropoxide group can undergo an elimination process to generate theHRVOC propylene. In an aspect, contacting a pre-catalyst with a nitrogencontaining compound as disclosed herein may be effective for removingthe isopropoxide groups from the support prior to the calcination step.In a further aspect, olefin polymerization catalysts produced asdisclosed herein may be characterized by HRVOC emissions that arereduced by from about 50% to about 95% when compared to the emissionsfrom an otherwise similar olefin polymerization catalyst prepared in theabsence of a nitrogen-containing compound, (e.g., an otherwise similarolefin polymerization catalyst wherein a pre-catalyst used to producethe olefin polymerization catalyst was not treated with an aqueousalkaline solution prior to being activated by calcination as disclosedherein). Alternatively, emissions of HRVOCs from olefin polymerizationcatalysts prepared as disclosed herein are reduced by greater than about50%; alternatively, greater than about 75%; %; alternatively, greaterthan about 90%; or alternatively, greater than about 95% compared to anotherwise similar olefin polymerization catalyst prepared in the absenceof the nitrogen-containing compound. In an aspect of the presentdisclosure, HRVOCs emissions during preparation of olefin polymerizationcatalysts of the type disclosed herein are less than about 5 wt. %;alternatively, less than about 2 wt. %; alternatively, less than about 1wt. %; or alternatively, less than about 0.5 wt. % based upon the totalweight of the olefin polymerization catalyst after completion of allprocessing steps (i.e., after activation via calcination).

The olefin polymerization catalysts of the present disclosure aresuitable for use in any olefin polymerization method, using varioustypes of polymerization reactors. In an aspect of the presentdisclosure, a polymer of the present disclosure is produced by anyolefin polymerization method, using various types of polymerizationreactors. As used herein, “polymerization reactor” includes any reactorcapable of polymerizing olefin monomers to produce homopolymers and/orcopolymers. Homopolymers and/or copolymers produced in the reactor maybe referred to as resin and/or polymers. The various types of reactorsinclude, but are not limited to those that may be referred to as batch,slurry, gas-phase, solution, high pressure, tubular, autoclave, or otherreactor and/or reactors. Gas-phase reactors may comprise fluidized bedreactors or staged horizontal reactors. Slurry reactors may comprisevertical and/or horizontal loops. High pressure reactors may compriseautoclave and/or tubular reactors. Reactor types may include batchand/or continuous processes. Continuous processes may use intermittentand/or continuous product discharge or transfer. Processes may alsoinclude partial or full direct recycle of un-reacted monomer, un-reactedcomonomer, olefin polymerization catalyst and/or co-catalysts, diluents,and/or other materials of the polymerization process.

Polymerization reactor systems of the present disclosure may compriseone type of reactor in a system or multiple reactors of the same ordifferent type, operated in any suitable configuration. Production ofpolymers in multiple reactors may include several stages in at least twoseparate polymerization reactors interconnected by a transfer systemmaking it possible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. Alternatively,polymerization in multiple reactors may include the transfer, eithermanual or automatic, of polymer from one reactor to subsequent reactoror reactors for additional polymerization. Alternatively, multi-stage ormulti-step polymerization may take place in a single reactor, whereinthe conditions are changed such that a different polymerization reactiontakes place.

The desired polymerization conditions in one of the reactors may be thesame as or different from the operating conditions of any other reactorsinvolved in the overall process of producing the polymer of the presentdisclosure. Multiple reactor systems may include any combinationincluding, but not limited to, multiple loop reactors, multiplegas-phase reactors, a combination of loop and gas-phase reactors,multiple high pressure reactors, and a combination of high pressure withloop and/or gas reactors. The multiple reactors may be operated inseries or in parallel. In an aspect of the present disclosure, anyarrangement and/or any combination of reactors may be employed toproduce the polymer of the present disclosure.

According to one aspect of the present disclosure, the polymerizationreactor system may comprise at least one loop slurry reactor. Suchreactors are commonplace, and may comprise vertical or horizontal loops.Generally, continuous processes may comprise the continuous introductionof a monomer, an olefin polymerization catalyst, and/or a diluent into apolymerization reactor and the continuous removal from this reactor of asuspension comprising polymer particles and the diluent. Monomer,diluent, olefin polymerization catalyst, and optionally any comonomermay be continuously fed to a loop slurry reactor, where polymerizationoccurs. Reactor effluent may be flashed to remove the liquids thatcomprise the diluent from the solid polymer, monomer and/or comonomer.Various technologies may be used for this separation step, including butnot limited to, flashing that may include any combination of heataddition and pressure reduction; separation by cyclonic action in eithera cyclone or hydrocyclone; separation by centrifugation; or otherappropriate method of separation.

Typical slurry polymerization processes (also known as particle-formprocesses), are disclosed in U.S. Pat. Nos. 3,248,179, 4,501,885,5,565,175, 5,575,979, 6,239,235, 6,262,191 and 6,833,415, for example;each of which are herein incorporated by reference in their entirety.

Diluents suitable for use in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is the polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another aspect of the present disclosure, thepolymerization reactor may comprise at least one gas-phase reactor. Suchsystems may employ a continuous recycle stream containing one or moremonomers continuously cycled through a fluidized bed in the presence ofthe olefin polymerization catalyst under polymerization conditions. Arecycle stream may be withdrawn from the fluidized bed and recycled backinto the reactor. Simultaneously, polymer product may be withdrawn fromthe reactor and new or fresh monomer may be added to replace thepolymerized monomer. Such gas-phase reactors may comprise a process formulti-step gas-phase polymerization of olefins, in which olefins arepolymerized in the gaseous phase in at least two independent gas-phasepolymerization zones while feeding an olefin polymerizationcatalyst-containing polymer formed in a first polymerization zone to asecond polymerization zone. One type of gas-phase reactor suitable foruse is disclosed in U.S. Pat. Nos. 4,588,790, 5,352,749, and 5,436,304,each of which is incorporated by reference in its entirety herein.

According to still another aspect of the present disclosure, ahigh-pressure polymerization reactor may comprise a tubular reactor oran autoclave reactor. Tubular reactors may have several zones wherefresh monomer, initiators, or olefin polymerization catalysts are added.Monomer may be entrained in an inert gaseous stream and introduced atone zone of the reactor. Initiators, olefin polymerization catalysts,and/or catalyst components may be entrained in a gaseous stream andintroduced at another zone of the reactor. The gas streams may beintermixed for polymerization. Heat and pressure may be employedappropriately to obtain optimal polymerization reaction conditions.

According to yet another aspect of the present disclosure, thepolymerization reactor may comprise a solution polymerization reactorwherein the monomer is contacted with the olefin polymerization catalystcomposition by suitable stirring or other means. A carrier comprising anorganic diluent or excess monomer may be employed. If desired, themonomer may be brought in the vapor phase and into contact with thecatalytic reaction product, in the presence or absence of liquidmaterial. The polymerization zone is maintained at temperatures andpressures that will result in the formation of a solution of the polymerin a reaction medium. Agitation may be employed to obtain bettertemperature control and to maintain uniform polymerization mixturesthroughout the polymerization zone. Adequate means are utilized fordissipating the exothermic heat of polymerization.

Polymerization reactors suitable for use in the present disclosure mayfurther comprise any combination of at least one raw material feedsystem, at least one feed system for an olefin polymerization catalystor catalyst components, and/or at least one polymer recovery system.Suitable reactor systems for the present disclosure may further comprisesystems for feedstock purification, catalyst storage and preparation,extrusion, reactor cooling, polymer recovery, fractionation, recycle,storage, loadout, laboratory analysis, and process control.

Conditions that are controlled for polymerization efficiency and toprovide polymer properties include, but are not limited to, temperature,pressure, type and quantity of the olefin polymerization catalyst orco-catalyst, and the concentrations of various reactants. Polymerizationtemperature can affect catalyst productivity, polymer molecular weightand molecular weight distribution. Suitable polymerization temperaturesmay be any temperature below the de-polymerization temperature,according to the Gibbs Free Energy Equation. Typically, this includesfrom about 60° C. to about 280° C., for example, and/or from about 70°C. to about 110° C., depending upon the type of polymerization reactorand/or polymerization process.

Suitable pressures will also vary according to the reactor andpolymerization process. The pressure for liquid phase polymerization ina loop reactor is typically less than 1000 psig (6.9 MPa). Pressure forgas-phase polymerization is usually in a range of from about 200 psig(1.4 MPa)-500 psig (3.45 MPa). High-pressure polymerization in tubularor autoclave reactors is generally run in a range of from about 20,000psig (138 MPa) to 75,000 psig (518 MPa). Polymerization reactors canalso be operated in a supercritical region occurring at generally highertemperatures and pressures. Operation at conditions above the criticalpoint as indicated by a pressure/temperature diagram (supercriticalphase), may offer advantages.

The concentration of various reactants can be controlled to producepolymers with certain physical and mechanical properties. The proposedend-use product that will be formed by the polymer and the method offorming that product may be varied to determine the desired finalproduct properties. Mechanical properties include, but are not limitedto tensile strength, flexural modulus, impact resistance, creep, stressrelaxation and hardness test values. Physical properties include, butare not limited to density, molecular weight, molecular weightdistribution, melting temperature, glass transition temperature,temperature melt of crystallization, density, stereoregularity, crackgrowth, short chain branching, long chain branching and rheologicalmeasurements.

The concentrations of monomer, comonomer, hydrogen, co-catalyst,modifiers, and electron donors are generally important in producingspecific polymer properties. Comonomer may be used to control productdensity. Hydrogen may be used to control product molecular weight.Co-catalysts may be used to alkylate, scavenge poisons and/or controlmolecular weight. The concentration of poisons may be minimized, aspoisons may impact the reactions and/or otherwise affect polymer productproperties. Modifiers may be used to control product properties andelectron donors may affect stereoregularity.

Polymers such as polyethylene homopolymers and copolymers of ethylenewith other mono-olefins may be produced in the manner described aboveusing the olefin polymerization catalysts prepared as described herein.Polymers produced as disclosed herein may be formed into articles ofmanufacture or end use articles using techniques known in the art suchas extrusion, blow molding, injection molding, fiber spinning,thermoforming, and casting. For example, a polymer resin may be extrudedinto a sheet, which is then thermoformed into an end use article such asa container, a cup, a tray, a pallet, a toy, or a component of anotherproduct. Examples of other end use articles into which the polymerresins may be formed include pipes, films, and bottles.

A method of the present disclosure comprises contacting an olefinpolymerization catalyst of the type described with an olefin monomerunder conditions suitable for the formation of a polyolefin andrecovering the polyolefin. In an aspect the olefin monomer is anethylene monomer and the polyolefin is an ethylene polymer(polyethylene).

Polyethylene prepared as described herein may be characterized by a highload melt index (HLMI), in a range of from about 1 g/10 min. to about500 g/10 min.; alternatively, from about 3 g/10 min. to about 300 g/10min.; alternatively, from about 10 g/10 min. to about 100 g/10 min.; oralternatively, from about 25 g/10 min. to about 50 g/10 min. In afurther aspect, the polyethylene prepared as described herein may becharacterized by an HLMI that is from about 1.1 to about 1.5 timesgreater than the HLMI of a polymer produced by utilizing an otherwisesimilar olefin polymerization catalyst produced in the absence of anitrogen-containing compound.

The HLMI represents the rate of flow of a molten polymer through anorifice of 0.0825 inch diameter when subjected to a force of 21,600grams at 190° C. as determined in accordance with ASTM D1238-82condition F.

EXAMPLES

The following examples are given as particular aspects of the presentdisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification or the claims to follow in anymanner.

In each experiment of the following examples HA30W, a Cr/silica catalystmade by W. R Grace, was dried at 200° C. and then titanated anhydrouslywith Ti(OiPr)₄ in heptane and dried. The various samples were thentreated, as listed below, prior to activation at 650° C. The finalcatalysts contained 3% Ti.

Activity tests were conducted in a 2.2 liter steel reactor equipped witha marine stirrer running at 400 rpm. The reactor was surrounded by asteel jacket circulating water, the temperature of which was controlledby use of steam and water heat exchangers. These were connected in anelectronic feed-back loop so that the reactor temperature could bemaintained at +/−0.5° C. during the reaction.

Unless otherwise stated, a small amount (0.01 to 0.10 grams normally) ofthe solid chromium catalyst was first charged under nitrogen to the dryreactor. Next about 0.25 g of sulfate-treated alumina (600° C.) wasadded as a scavenger for poisons. Then 1.2 liter of isobutane liquid wascharged and the reactor heated up to the specified temperature, usually105° C. Finally, ethylene was added to the reactor to equal a fixedpressure, normally 550 psig (3.8 MPa), which was maintained during theexperiment. The stirring was allowed to continue for the specified time,usually around one hour, and the activity was noted by recording theflow of ethylene into the reactor to maintain the set pressure.

After the allotted time, the ethylene flow was stopped and the reactorslowly depressurized and opened to recover a granular polymer powder. Inall cases the reactor was clean with no indication of any wall scale,coating or other forms of fouling. The polymer powder was then removedand weighed. Activity was specified as grams of polymer produced pergram of solid catalyst charged per hour.

Example 1

The first series of experiments studied the ability of base treatment,of an anhydrously titanated support dissolved in solution, to maintainthe titanation of the support and provide effective titanation to acatalyst. The results are listed in Table 1. Runs 1.1 and 1.2 arecomparative runs and were not exposed to a base treatment. Run 1.3 useda titanated support prepared as described above. After treatment withTi(OiPr)₄, the liquid mixture containing the titanated support wasexposed to a mixture of MeOH and NH₄OH vapor in a 70/30 volume ratio at160° C. for 24 hours by bubbling the MeOH/NH₄OH vapor through the liquidmixture containing the titanated support. The melt index data of Run 1.3shows that base treatment did not degrade catalyst performance butresulted in an increase of greater than 10% in the HLMI value withrespect to the comparative runs.

TABLE 1 Anhydrously-Titanated Supports Treated with MeOH/NH₄OH Ind. RunTime Prod Activity MI I10 HLMI No. Treatment min gig g/g-h dg/min dg/mindg/min 1.1 None 11 2455 1259 0.23 4.69 21.5 1.2 None 5 2271 2349 0.295.91 28.0 1.3 MeOH + 5 2511 1815 0.38 6.68 31.2 NH₄OH vapor 160° C., 24h

Example 2

The next series of experiments studied the ability of base treatment ofa solid, anhydrously titanated support to maintain the titanation of thesupport and provide effective titanation to a catalyst. In theseexperiments, a silica support like that used above was again titanatedvia the same procedure described. This served as the base catalyst forthe finishing treatment experiments.

The results of different post-treatments are listed in Table 2. Acomparative run was also conducted (Run 2.1) in which the catalyst wasgiven no post-treatment. In Run 2.2 the solid titanated support wasexposed to n-propanol vapor at 200° C. for 3 hours and one can see theloss in melt index potential that this caused. Propanol, and otheralcohols, are thought to hydrolyze the Si—O—Ti bond, thus destroying theeffectiveness of the Ti. In Run 2.3, the titanated support was washed inaqueous NH₄OH solution (5 wt. %), and then dried and calcined in theusual manner. The HLMI value for the base-washed catalyst was nearly 30%greater than the comparative run and suggested that the hydrolysis ofSi—O—Ti bonds known to occur during calcination had been repressed bythe base wash. In Run 2.4, the same procedure used to produce thetitanated catalyst of Run 2.2 was employed again. After the titanatedsupport was washed with aqueous NH₄OH the catalyst of Run 2.4 wasexposed to methanol vapor at 160° C. for 24 hours. The degradation tothe melt index potential observed between Runs 2.3 and 2.4 may again beexplained by hydrolysis of the Si—O—Ti bonds, however, the degradationwas less severe than what was observed in Run 2.2 that did not includetreating the titanated support with NH₄OH hydroxide before prolongedexposure to hot alcohol vapor. Some of the protective effect of theNH₄OH treatment held up even though it evaporated during the heattreatment.

In Run 2.5 the titanated support was dry-mixed with urea beforeactivation and was not washed with aqueous NH₄OH. This experiment wasdesigned to capture the ammonia produced by decomposition of urea thatoccurs at elevated temperatures. However, urea decomposition occurs atjust slightly above 100° C., and this approach may not be useful athigher temperatures.

TABLE 2 Dried Titanated Supports Washed with NH₄OH Run Ind. Time ProdActivity MI I10 HLMI No. Treatment min g/g g/g-h dg/min dg/min dg/min2.1 None 8 2534 2715 0.40 7.70 36.7 2.2 PrOH, 18 2990 3590 0.17 3.5 18.4200° C. 2.3 NH₄OH 8 2676 4013 0.59 10.4 47.7 Wash NH₄OH wash 2.4 MeOH 52781 4391 0.28 5.85 27.3 vapor 160° C. 24 h 2.5 Dry mix 13 3319 34330.33 6.3 30.6 urea

Example 3

The next series of experiments studied whether washing a pre-catalystwith aqueous base prior to activation would hydrolyze residualTi-isopropoxide bonds and reduce the amount of carbon retained on thepre-catalyst. Pre-catalysts that had not been calcined were obtained,Run 3.1 was not treated further and Run 3.2 was washed with aqueousbase. Both samples were analyzed for residual carbon, nitrogen, hydrogenand sulfur by combustion analysis and the results are shown in Table 3.The aqueous base wash resulted in a reduction of retained carbon ofgreater than 90%. Retained carbon in the form of isopropoxide groups isat least partly responsible for the emission of VOCs and HRVOCs producedduring activation of the catalyst described herein. The experimentalresults suggest that washing a pre-catalyst with an aqueous base priorto activation could reduce the amount of HRVOCs emitted duringproduction the catalyst as disclosed herein.

TABLE 3 Reduction in Elemental Emissions by Aqueous Base Wash Run No.Treatment Carbon % Hydrogen % Nitrogen % Sulfur % 3.1 None 4.84 1.990.01 0.001 3.2 NH₄OH 0.40 1.44 0.41 0.001

ADDITIONAL DISCLOSURE

The following enumerated aspects of the present disclosures are providedas non-limiting examples.

A first aspect which is a method of preparing a hydrolyzed pre-catalystcomprising: a) drying a silica support by heating the silica support toa temperature in a range of from about 150° C. to about 250° C. andmaintaining the temperature of the silica support in the range of fromabout 150° C. to about 250° C. for a time period of from about 1 hour toabout 24 hours to form a dried support; b) contacting the dried supportand a titanium(IV) alkoxide to form a titanated support; c) drying thetitanated support by heating the titanated support to a temperature in arange of from about 50° C. to about 200° C. and maintaining thetemperature of the titanated support in the range of from about 50° C.to about 200° C. for a time period of from about 30 minutes to about 6hours to form a dried titanated support; d) contacting the driedtitanated support and an aqueous alkaline solution comprising from about3 wt. % to about 20 wt. % of a nitrogen-containing compound for a timeperiod of from about 10 minutes to about 6 hours to form a mixturecomprising a hydrolyzed titanated support wherein a weight ratio of theamount of aqueous alkaline solution to the amount of titanium(IV)alkoxide in the dried titanated support is from about 30:1 to about 3:1;and e) removing the hydrolyzed titanated support from the mixturecomprising the hydrolyzed titanated support and drying the hydrolyzedtitanated support by heating the hydrolyzed titanated support to atemperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature of the hydrolyzed titanated support in therange of from about 50° C. to about 200° C. for a time period of fromabout 30 minutes to about 6 hours to form the hydrolyzed pre-catalyst.

A second aspect which is the method of the first aspect furthercomprising: contacting, to form a pre-catalyst, a chromium-containingcompound and at least one material selected from the group consisting ofthe silica support, the dried support, the titanated support, the driedtitanated support, the mixture comprising the hydrolyzed titanatedsupport, and the hydrolyzed pre-catalyst; and calcining the pre-catalystby heating the pre-catalyst to a temperature in a range of from about400° C. to about 1000° C. and maintaining the temperature of thepre-catalyst in the range of from about 400° C. to about 1000° C. for atime period of from about 1 minute to about 24 hours to form a catalyst.

A third aspect which is the method of the second aspect wherein anamount of highly reactive volatile organic compounds (HRVOC) emittedduring calcining the pre-catalyst is reduced by from about 80% to about95%, as determined by combustion analysis in accordance withEnvironmental Protection Agency (EPA) Method 18-type/American Societyfor Testing and Materials (ASTM) D1946, when compared to the amount ofHRVOC emitted during calcining an otherwise similar pre-catalystprepared in the absence of an aqueous alkaline solution.

A fourth aspect which is the method of the second aspect wherein anamount of HRVOC emitted during calcining the pre-catalyst is less thanabout 1 wt. % as determined by combustion analysis in accordance withEPA Method 18-type/ASTM D1946.

A fifth aspect which is the method of any of the first four aspectswherein the nitrogen-containing compound comprises an amide, an amidine,an amine, a diamine, a triamine, an amino acid, an ammonium hydroxide, aformamide, a hydrazine, a hydroxylamine, an imidazole, a piperazine, apiperidine, a pyrazine, a pyrazole, a pyridine, a pyrimidine, a pyrrole,a urea, or a combination thereof.

A sixth aspect which is the method of any of the first five aspectswherein the nitrogen-containing compound has Structure 1, Structure 2,Structure 3, or Structure 4: where each R¹, each R², and each R³ areindependently hydrogen, a C₁ to C₆ organyl group or a C₁ to C₆ arylgroup; each R⁴ is CH₃ or C₂H₅, and R⁵ is hydrogen, CH₃, OH, or OCH₃.

-   -   N(R¹)₃ N(R²)₄OH N(R³)₂OH    -   Structure 1 Structure 2 Structure 3

A seventh aspect which is the method of any of the first six aspectswherein the nitrogen-containing compound comprises ammonia, ammoniumhydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide,hydrazine, hydroxylamine, triethyl amine, trimethyl amine, acetamide,creatine, 1,4-diazabicyclo[2.2.2]octane (DABCO),1,5-diazabicyclo[4.3.0]non-5-ene (DBN),1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), N,N-diisopropylethylamine(DIPEA), dimethyl carbamate, formamide, methyl formamide, dimethylformamide, dimethyl glycine, 1,4-dimethylpiperazine (DMP), 1,3-dimethylurea, imidazole, piperazine, piperidine, pyrazine, pyrazole, pyridine,pyrimidine, pyrrole, tetramethylethylenediamine (TMEDA), triazine,1,3,5-triazacyclohexane, 1,3,5-trimethyl-1,3,5-triazacyclohexane(TMTAC), or a combination thereof.

An eighth aspect which is the method of any of the first seven aspectswherein the titanium(IV) alkoxide comprises titanium(IV) ethoxide,titanium(IV) isopropoxide, titanium(IV) n-propoxide, titanium(IV)n-butoxide, titanium(IV) isobutoxide, or a combination thereof.

A ninth aspect which is the method of any of the first eight aspectswherein the titanium(IV) alkoxide comprises titanium(IV) isopropoxide.

A tenth aspect which is the method of any of the first nine aspectswherein the silica support is characterized by a surface area of fromabout 100 m²/gram to about 1000 m²/gram and a pore volume of from about1.0 cm³/gram to about 2.5 cm³/gram.

An eleventh aspect which is the method of any of the second throughtenth aspects wherein the chromium-containing compound compriseschromium trioxide, chromium acetate, chromium nitrate, tertiary butylchromate, biscyclopentadienyl chromium(II), chromium(III)acetylacetonate, or a combination thereof.

A twelfth aspect which is the method of any of the second througheleventh aspects wherein an amount of titanium present in the catalystranges from about 0.01% to about 10% by total weight of the catalyst.

A thirteenth aspect which is the method of any of the second throughtwelfth aspects wherein an amount of chromium present in the catalystranges from about 0.01% to about 10% by total weight of the catalyst.

A fourteenth aspect which is a method of forming an ethylene polymercomprising contacting the catalyst prepared by the method of any of thesecond through twelfth aspects with an ethylene monomer under conditionssuitable for formation of the ethylene polymer and recovering theethylene polymer.

A fifteenth aspect which is the method of the fourteenth aspect whereinthe ethylene polymer has a high load melt index (HLMI) that is fromabout 10% to about 100% greater than the HLMI of an ethylene polymerproduced by utilizing an otherwise similar catalyst produced in theabsence of an aqueous alkaline solution.

A sixteenth aspect which is a method of preparing a hydrolyzedpre-catalyst comprising: a) drying a silica support by heating thesilica support to a temperature in a range of from about 150° C. toabout 250° C. and maintaining the temperature of the silica support inthe range of from about 150° C. to about 250° C. for a time period offrom about 1 hour to about 24 hours to form a dried support; b)contacting the dried support and a titanium(IV) alkoxide to form atitanated support; c) heating the titanated support to a temperature ina range of from about 50° C. to about 200° C. and maintaining thetemperature in the range of from about 50° C. to about 200° C. whilecontacting the titanated support and an alkaline material for a timeperiod of from about 2 hours to about 48 hours; d) ceasing contacting ofthe titanated support and the alkaline material to provide a hydrolyzedsupport having a temperature in a range of from about 50° C. to about200° C.; and e) maintaining the temperature of the hydrolyzed support inthe range of from about 50° C. to about 200° C. for a time period offrom about 30 minutes to about 6 hours to form the hydrolyzedpre-catalyst.

A seventeenth aspect which is the method of the sixteenth aspect furthercomprising contacting, to form a pre-catalyst, a chromium-containingcompound and at least one material selected from the group consisting ofthe silica support, the dried support, the titanated support, thehydrolyzed support, and the hydrolyzed pre-catalyst; and calcining thepre-catalyst by heating the pre-catalyst to a temperature in a range offrom about 400° C. to about 1000° C. and maintaining the temperature ofthe pre-catalyst in the range of from about 400° C. to about 1000° C.for a time period of from about 1 minute to about 24 hours to form acatalyst.

An eighteenth aspect which is the method of the seventeenth aspectwherein an amount HRVOC emitted during calcining the pre-catalyst isreduced by from about 80% to about 95%, as determined by combustionanalysis in accordance with EPA Method 18-type/ASTM D1946, when comparedto the amount of HRVOC emitted during calcining an otherwise similarpre-catalyst prepared in the absence of an alkaline material.

A nineteenth aspect which is the method of the seventeenth aspectwherein an amount HRVOC emitted during calcining the pre-catalyst isless than about 1 wt. % as determined by combustion analysis inaccordance with EPA Method 18-type/ASTM D1946.

A twentieth aspect which is the method of the sixteenth aspect whereinthe alkaline material comprises a vapor associated with a basic liquidwherein the basic liquid comprises an aqueous solution of anitrogen-containing compound and optionally an alcohol wherein an amountof nitrogen-containing compound in the aqueous solution is from about 3wt. % to about 20 wt. % wherein a volumetric ratio of the aqueoussolution to the alcohol is from about 7:3 to about 3:7 and wherein thealcohol is methanol, ethanol, n-propanol, isopropanol, or a combinationthereof.

A twenty-first aspect which is the method of the sixteenth aspectwherein the alkaline material is an aqueous alkaline solution comprisinga nitrogen-containing compound in an amount from about 3 wt. % to about20 wt. % wherein a weight ratio of the amount of aqueous alkalinesolution to the amount of titanium(IV) alkoxide in the titanated supportis from about 30:1 to about 3:1.

A twenty-second aspect which is the method of any of the sixteenththrough twenty-first aspects wherein the alkaline material comprises anamide, an amidine, an amine, a diamine, a triamine, an amino acid, anammonium hydroxide, a formamide, a hydrazine, a hydroxylamine, animidazole, a piperazine, a piperidine, a pyrazine, a pyrazole, apyridine, a pyrimidine, a pyrrole, a urea, or a combination thereof.

A twenty-third aspect which is the method of any of the sixteenththrough twenty-second aspects wherein the alkaline material hasStructure 1, Structure 2, Structure 3, or Structure 4: where each R¹,each R², and each R³ are independently hydrogen, a C₁ to C₆ organylgroup or a C₁ to C₆ aryl group; each R⁴ is CH₃ or C₂H₅; and R⁵ ishydrogen, CH₃, OH, or OCH₃.

-   -   N(R¹)₃ N(R²)₄OH N(R³)₂OH    -   Structure 1 Structure 2 Structure 3

A twenty-fourth aspect which is the method of any of the sixteenththrough twenty-third aspects wherein the alkaline material comprisesammonia, ammonium hydroxide, tetraethylammonium hydroxide,tetramethylammonium hydroxide, hydrazine, hydroxylamine, triethyl amine,trimethyl amine, acetamide, creatine, 1,4-diazabicyclo[2.2.2]octane(DABCO), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN),1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), N,N-diisopropylethylamine(DIPEA), dimethyl carbamate, formamide, methyl formamide, dimethylformamide, dimethyl glycine, 1,4-dimethylpiperazine (DMP), 1,3-dimethylurea, imidazole, piperazine, piperidine, pyrazine, pyrazole, pyridine,pyrimidine, pyrrole, tetramethylethylenediamine (TMEDA), triazine,1,3,5-triazacyclohexane, 1,3,5-trimethyl-1,3,5-triazacyclohexane(TMTAC), or a combination thereof.

A twenty-fifth aspect which is the method of any of the sixteenththrough twenty-fourth aspects wherein the titanium(IV) alkoxidecomprises titanium(IV) ethoxide, titanium(IV) isopropoxide, titanium(IV)n-propoxide, titanium(IV) n-butoxide, titanium(IV) isobutoxide, or acombination thereof.

A twenty-sixth aspect which is the method of the seventeenth aspectwherein an amount of chromium present in the catalyst ranges from about0.01% to about 10% by total weight of the catalyst.

A twenty-seventh aspect which is a method of preparing a catalystcomprising: a) drying a chrominated-silica support by heating thechrominated-silica support to a temperature in a range of from about150° C. to about 250° C. and maintaining the temperature of thechrominated-silica support in the range of from about 150° C. to about250° C. for a time period of from about 1 hour to about 24 hours to forma dried chrominated-silica support; b) contacting the driedchrominated-silica support and a titanium(IV) alkoxide to form ametalized support; c) drying the metalized support by heating themetalized support to a temperature in a range of from about 50° C. toabout 200° C. and maintaining the temperature of the metalized supportin the range of from about 50° C. to about 200° C. for a time period offrom about 30 minutes to about 6 hours to form a dried metalizedsupport; d) contacting the dried metalized support and an aqueousalkaline solution comprising from about 3 wt. % to about 20 wt. % of anitrogen-containing compound for a time period of from about 10 minutesto about 6 hours to form a mixture comprising a hydrolyzed metalizedsupport wherein a weight ratio of the amount of aqueous alkalinesolution to the amount of titanium(IV) alkoxide in the dried metalizedsupport is from about 30:1 to about 3:1; e) removing the hydrolyzedmetalized support from the mixture comprising the hydrolyzed metalizedsupport and drying the hydrolyzed metalized support by heating thehydrolyzed metalized support to a temperature in a range of from about50° C. to about 200° C. and maintaining the temperature of thehydrolyzed metalized support in the range of from about 50° C. to about200° C. for a time period of from about 30 minutes to about 6 hours toform a pre-catalyst; and f) calcining the pre-catalyst by heating thepre-catalyst to a temperature in a range of from about 400° C. to about1000° C. and maintaining the temperature of the pre-catalyst in therange of from about 400° C. to about 1000° C. for a time period of fromabout 1 minute to about 24 hours to form the catalyst.

A twenty-eighth aspect which is a method of preparing a catalystcomprising: a) drying a silica support by heating the silica support toa temperature in a range of from about 150° C. to about 250° C. andmaintaining the temperature of the silica support in the range of fromabout 150° C. to about 250° C. for a time period of from about 1 hour toabout 24 hours to form a dried support; b) contacting the dried supportand a titanium(IV) alkoxide to form a titanated support; c) drying thetitanated support by heating the titanated support to a temperature in arange of from about 50° C. to about 200° C. and maintaining thetemperature of the titanated support in the range of from about 50° C.to about 200° C. for a time period of from about 30 minutes to about 6hours to form a dried titanated support; d) contacting the driedtitanated support and an aqueous alkaline solution comprising from about3 wt. % to about 20 wt. % of a nitrogen-containing compound for a timeperiod of from about 10 minutes to about 6 hours to form a mixturecomprising a hydrolyzed titanated support wherein a weight ratio of theamount of aqueous alkaline solution to the amount of titanium(IV)alkoxide in the dried titanated support is from about 30:1 to about 3:1;e) removing the hydrolyzed titanated support from the mixture comprisingthe hydrolyzed titanated support and drying the hydrolyzed titanatedsupport by heating the hydrolyzed titanated support to a temperature ina range of from about 50° C. to about 200° C. and maintaining thetemperature of the hydrolyzed titanated support in the range of fromabout 50° C. to about 200° C. for a time period of from about 30 minutesto about 6 hours to form a hydrolyzed pre-catalyst; f) contacting, toform a pre-catalyst, a chromium-containing compound and at least onematerial selected from the group consisting of the silica support, thedried support, the titanated support, the dried titanated support, themixture comprising the hydrolyzed titanated support, and the hydrolyzedpre-catalyst; and g) calcining the pre-catalyst by heating thepre-catalyst to a temperature in a range of from about 400° C. to about1000° C. and maintaining the temperature of the pre-catalyst in therange of from about 400° C. to about 1000° C. for a time period of fromabout 1 minute to about 24 hours to form the catalyst.

A twenty-ninth aspect which is a method of preparing a catalystcomprising: a) drying a chrominated-silica support by heating thechrominated-silica support to a temperature in a range of from about150° C. to about 250° C. and maintaining the temperature of thechrominated-silica support in the range of from about 150° C. to about250° C. for a time period of from about 1 hour to about 24 hours to forma dried chrominated-silica support; b) contacting the driedchrominated-silica support and a titanium(IV) alkoxide to form ametalized support; c) heating the metalized support to a temperature ina range of from about 50° C. to about 200° C. and maintaining thetemperature in the range of from about 50° C. to about 200° C. whilecontacting the metalized support and a gas-phase solution material for atime period of from about 2 hours to about 48 hours; d) ceasingcontacting of the metalized support and the gas-phase solution toprovide a hydrolyzed metalized support having a temperature in a rangeof from about 50° C. to about 200° C.; e) maintaining the temperature ofthe hydrolyzed metalized support in the range of from about 50° C. toabout 200° C. for a time period of from about 30 minutes to about 6hours to form a pre-catalyst; and f) calcining the pre-catalyst byheating the pre-catalyst to a temperature in a range of from about 400°C. to about 1000° C. and maintaining the temperature of the pre-catalystin the range of from about 400° C. to about 1000° C. for a time periodof from about 1 minute to about 24 hours to form the catalyst.

A thirtieth aspect which is a method of preparing a catalyst comprising:a) drying a silica support by heating the silica support to atemperature in a range of from about 150° C. to about 250° C. andmaintaining the temperature of the silica support in the range of fromabout 150° C. to about 250° C. for a time period of from about 1 hour toabout 24 hours to form a dried support; b) contacting the dried supportand a titanium(IV) alkoxide to form a titanated support; c) heating thetitanated support to a temperature in a range of from about 50° C. toabout 200° C. and maintaining the temperature in the range of from about50° C. to about 200° C. while contacting the titanated support and agas-phase solution for a time period of from about 2 hours to about 48hours; d) ceasing contacting of the titanated support and the gas-phasesolution to provide a hydrolyzed support having a temperature in a rangeof from about 50° C. to about 200° C.; e) maintaining the temperature ofthe hydrolyzed support in the range of from about 50° C. to about 200°C. for a time period of from about 30 minutes to about 6 hours to form ahydrolyzed pre-catalyst; f) contacting, to form a pre-catalyst, achromium-containing compound and at least one material selected from thegroup consisting of the silica support, the dried support, the titanatedsupport, the hydrolyzed support, and the hydrolyzed pre-catalyst; and g)calcining the pre-catalyst by heating the pre-catalyst to a temperaturein a range of from about 400° C. to about 1000° C. and maintaining thetemperature of the pre-catalyst in the range of from about 400° C. toabout 1000° C. for a time period of from about 1 minute to about 24hours to form the catalyst.

The terms “a”, “an”, and “the” are intended, unless specificallyindicated otherwise, to include plural alternatives, e.g., at least one.Herein, while methods and processes are described in terms of“comprising” various components or steps, the methods and processes canalso “consist essentially of” or “consist of” the various components orsteps. A particular feature of the disclosed subject matter can bedisclosed as follows: Feature X can be A, B, or C. It is alsocontemplated that for each feature the statement can also be phrased asa listing of alternatives such that the statement “Feature X is A,alternatively B, or alternatively C” is also an aspect of the presentdisclosure whether or not the statement is explicitly recited.

While various aspects of the present disclosure have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the presentdisclosure. The aspects of the present disclosure described herein areexemplary only and are not intended to be limiting. Many variations andmodifications of the present disclosure are possible and are within thescope of the present disclosure. Where numerical ranges or limitationsare expressly stated, such express ranges or limitations should beunderstood to include iterative ranges or limitations of like magnitudefalling within the expressly stated ranges or limitations (e.g., “fromabout 1 to about 10” includes, 2, 3, 4, etc.; “greater than 0.10”includes 0.11, 0.12, 0.13, etc.). Use of the term “optionally” withrespect to any element of a claim is intended to mean that the subjectelement is required, or alternatively, is not required. Bothalternatives are intended to be within the scope of the claim. Use ofbroader terms such as “comprises”, “includes”, “having”, etc. should beunderstood to provide support for narrower terms such as “consistingof”, “consisting essentially of”, “comprised substantially of”, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an aspect of thepresent disclosure. Thus, the claims are a further description and arean addition to the aspect of the present disclosure. The discussion of areference in the present disclosure is not an admission that it is priorart to the present disclosure, especially any reference that may have apublication date after the priority date of this application. Thepresent disclosures of all patents, patent applications, andpublications cited herein are hereby incorporated by reference, to theextent that they provide exemplary, procedural or other detailssupplementary to those set forth herein.

All publications, patent applications, and patents mentioned herein areincorporated by reference in their entirety. In the event of conflict,the present specification, including definitions, is intended tocontrol. With respect to all ranges disclosed herein, such ranges areintended to include any combination of the mentioned upper and lowerlimits even if the particular combination is not specifically listed.

What is claimed is:
 1. A method of preparing a hydrolyzed pre-catalystcomprising: a) drying a silica support by heating the silica support toa temperature in a range of from about 150° C. to about 250° C. andmaintaining the temperature of the silica support in the range of fromabout 150° C. to about 250° C. for a time period of from about 1 hour toabout 24 hours to form a dried support; b) contacting the dried supportand a titanium(IV) alkoxide to form a titanated support; c) heating thetitanated support to a temperature in a range of from about 50° C. toabout 200° C. and maintaining the temperature in the range of from about50° C. to about 200° C. while contacting the titanated support and analkaline material for a time period of from about 2 hours to about 48hours; d) ceasing contacting of the titanated support and the alkalinematerial to provide a hydrolyzed support having a temperature in a rangeof from about 50° C. to about 200° C.; and e) maintaining thetemperature of the hydrolyzed support in the range of from about 50° C.to about 200° C. for a time period of from about 30 minutes to about 6hours to form the hydrolyzed pre-catalyst.
 2. The method of claim 1,wherein the titanium(IV) alkoxide comprises titanium(IV) ethoxide,titanium(IV) isopropoxide, titanium(IV) n-propoxide, titanium(IV)n-butoxide, titanium(IV) isobutoxide, or a combination thereof.
 3. Themethod of claim 1, wherein the titanium(IV) alkoxide is titanium(IV)isopropoxide.
 4. The method of claim 1, wherein the silica supportcomprises greater than about 50 wt. % silica based upon a total weightof the silica support.
 5. The method of claim 1, wherein the silicasupport has a surface area in a range of from about 100 m²/gram to about1000 m²/gram.
 6. The method of claim 1, wherein the alkaline materialcomprises a vapor associated with a basic liquid, wherein the basicliquid comprises an aqueous solution of a nitrogen-containing compoundand optionally an alcohol, wherein an amount of the nitrogen-containingcompound in the aqueous solution is from about 3 wt. % to about 20 wt. %based on a total weight of the aqueous solution, wherein a volumetricratio of the aqueous solution to the alcohol is from about 7:3 to about3:7 and wherein the alcohol is methanol, ethanol, n-propanol,isopropanol, or a combination thereof.
 7. The method of claim 6, whereinthe basic liquid comprises ammonium hydroxide present in the aqueoussolution in an amount of from about 3 wt. % to about 10 wt. % based uponthe total weight of the aqueous solution.
 8. The method of claim 1,wherein the alkaline material is an aqueous alkaline solution comprisinga nitrogen-containing compound in an amount from about 3 wt. % to about20 wt. %, wherein a weight ratio of the amount of the aqueous alkalinesolution to the amount of titanium(IV) alkoxide in the titanated supportis from about 30:1 to about 3:1.
 9. The method of claim 6, wherein thenitrogen-containing compound has Structure 1, Structure 2, Structure 3,Structure 4, or a combination thereof, N(R¹)₃ N(R²)₄OH N(R³)₂OHStructure 1 Structure 2 Structure 3

wherein R¹, R², R³, R⁴, and/or R⁵ are each independently hydrogen, anorganyl group, a hydrocarbyl group, or an aryl group.
 10. The method ofclaim 8, wherein the nitrogen-containing compound has Structure 1,Structure 2, Structure 3, Structure 4, or a combination thereof, N(R¹)₃N(R²)₄OH N(R³)₂OH Structure 1 Structure 2 Structure 3

wherein R¹, R², R³, R⁴, and/or R⁵ are each independently hydrogen, anorganyl group, a hydrocarbyl group, or an aryl group.
 11. The method ofclaim 8, wherein the aqueous alkaline solution further comprises aco-solvent.
 12. The method of claim 11, wherein the co-solvent comprisesan alcohol, an ester, a ketone, or a combination thereof.
 13. The methodof claim 1, wherein the alkaline material comprises an amide, anamidine, an amine, a diamine, a triamine, an amino acid, an ammoniumhydroxide, a formamide, a hydrazine, a hydroxylamine, an imidazole, apiperazine, a piperidine, a pyrazine, a pyrazole, a pyridine, apyrimidine, a pyrrole, a urea, or a combination thereof.
 14. The methodof claim 1, further comprising contacting, to form a pre-catalyst, achromium-containing compound and at least one material selected from thegroup consisting of the silica support, the dried support, the titanatedsupport, the hydrolyzed support, and the hydrolyzed pre-catalyst; andcalcining the pre-catalyst by heating the pre-catalyst to a temperaturein a range of from about 400° C. to about 1000° C. and maintaining thetemperature of the pre-catalyst in the range of from about 400° C. toabout 1000° C. for a time period of from about 1 minute to about 24hours to form a catalyst.
 15. The method of claim 14, wherein thechromium-containing compound comprises a water-soluble chromium compoundor, a hydrocarbon-soluble chromium compound.
 16. The method of claim 15,wherein the water-soluble chromium compound comprises chromium trioxide,chromium acetate, chromium nitrate, or a combination thereof.
 17. Themethod of claim 14, wherein the chromium-containing compound compriseschromium(III) carboxylates, chromium(III) naphthenates, chromium(III)halides, chromium(III) sulfates, chromium(III) nitrates, chromium(III)dionates, or a combination thereof.
 18. The method of claim 14, whereinthe chromium is present in an amount of from about 0.01 wt. % to about10 wt. % based upon a total weight of the catalyst.
 19. The method ofclaim 1, wherein an amount HRVOC emitted during calcining thepre-catalyst is reduced by from about 80% to about 95%, as determined bycombustion analysis in accordance with EPA Method 18-type/ASTM D1946,when compared to the amount of HRVOC emitted during calcining anotherwise similar pre-catalyst prepared in an absence of an alkalinematerial.
 20. The method of claim 1, wherein an amount HRVOC emittedduring calcining the pre-catalyst is less than about 1 wt. % asdetermined by combustion analysis in accordance with EPA Method18-type/ASTM D1946.